Odd Red color cast in Basketball Photos

Hey Everyone! I have a question concerning some basketball photos (below). I am getting a red color cast in some of my photos. After looking at the lighting in the gym I think I know why I am getting some of this (the lighting in the gym is set up so that the light are positioned with the outline of the court giving a red falloff on the walls). What I don't understand is why some photos have the red cast and some do not... I will try and put up to successive shot to show this. I am using a Canon Rebel xt (part of the problem I'm sure) and my favorite lens the Canon 50 1.4... I set my white balance to tungsten and got a little better outcome in some of the shots. But if you have any insight into what I can do to fix this, outside of getting a new camera (which I am soon to do with a 7D) it would be most helpful!

Gym lights, especially, cycle through several weird colors and intensities many times per second. To correct your color problems, you might shoot on WB AUTO, and record on RAW so you can adjust color temperature easily later. Shoot lots of pictures to compensate for the weird light. Another way around this will be to set up a couple strobes to light your shots in the dim light. Or, if you're careful with the moments you try to capture, you could shoot at 1/60, which syncs up with the lights and captures a full light-cycle with each shutter.

[[What I don't understand is why some photos have the red cast and some do not...]]

As Benjamin points out, lights flicker and do so at 120Hz. During that time the color coming from the lights changes. Your eyes cannot see this but with a fast enough shutter speed, your camera can capture it, as it has done here.

ahh ok... that makes sense. I have considered shooting the games in RAW to see if it would help in post processing. Thanks I will give it a try... also I am going to try and set up my 580ex2 speedlight off camera...

I had a similar problem under high school football lights and found that if I changed from spot or center-weighted metering to matrix metering, the color rarely changes within a sequence of shots. Good luck.